1. Field of the Invention
The present invention relates to a break display apparatus for a semiconductor switching element incorporating an overcurrent/overheating protection function for displaying that it has been broken due to overcurrent or overheating.
2. Description of the Related Art
A switching element or device incorporating an overcurrent/overheating protection function (hereinafter referred to as "intelligent power IC") generally includes a detection unit and a break unit. In operation, when the detection unit detects overcurrent or overheating for a load, on the basis of a detected signal, the break unit breaks to stop the power supply to the load. Such a previously known intelligent power IC is shown in FIG. 11. As seen from FIG. 11, on a printed circuit board 10 are provided intelligent power ICs 12a and 12b and a control IC 14. Loads 20a and 20b corresponding to the intelligent power ICs 12a and 12b are also provided.
In such a circuit configuration, when either of the intelligent power ICs breaks due to overcurrent or overheating, a diagnosis device 30 is connected to a dedicated connector 32 to decide the cause of break. In this case, communication of information is necessary between the control IC 14 and the diagnosis device 30. Therefore, software is required to effect the communication of information.
However, addition of an intelligent power IC requires to change the software for the control IC 14 and that for the diagnosis device 30. This necessitates a large number of man-hours. Further, excess cost is required to fabricate a simple control system.
On the other hand, known techniques using the above diagnosis device are disclosed in Japanese Utility Model Unexamined Publication Nos. Hei. 2-147355 and Hei. 3-83133. In the technique disclosed in Japanese Utility Model Unexamined Publication No. Hei. 2-147355, a signal from a fault diagnosis device is digital-processed by a fault detecting means to detect the fault, and the signal stored in a storage device is analog-displayed to decide the place of the fault.
In the technique disclosed in Japanese Utility Model Unexamined Publication No. Hei. 3-83133, the presence or absence of fault in various kinds of circuit components is self-diagnosed by an electronic control device. The code signal corresponding to the faulty component detected by the self-diagnosis function of the electronic control device is supplied into a display device and the character signal corresponding to the code signal is outputted on the display device so that the faulty component is displayed by characters on a display area.
However, these known techniques, because of using the diagnosis device, lead to great cost.